For the manufacture of metal monolith catalytic converters for use in motor vehicle exhaust systems to reduce certain engine exhaust gases, it has been proposed to wind a strip of herringbone or strips of corrugated and flat stainless steel foil to form a metallic substrate unit. This unit is then coated with a suitable catalyst and is typically either inserted in a housing or itself has a shell to which inlet and outlet housing pieces are added to complete the catalytic converter assembly. There are, however, problems with a wound foil substrate that result from vibrational, thermal and flow-imposing stresses which can cause the foil layers to telescope, i.e. adjacent layers of the foil slip past each other in an axial direction, thereby unraveling the substrate. This can occur with both herringbone foils and flat-corrugated foils. Heretofore, the solutions to this problem have been to braze or weld the foil layers together or to provide some mechanical means of holding the substrate together such as with end retainer rings, pins, staples and/or interlocking features on the foil itself. While such previous solutions have proved generally satisfactory, they also incur significant costs to the manufacture of the substrate.